An internal combustion engine commonly employs a pressurized cooling system with a circulating liquid coolant for cooling the engine. Engine heat is transferred from the engine to the coolant in a cooling jacket surrounding combustion heated parts of the engine. The heat absorbed by the circulated coolant is generally dissipated by a heat exchanger into the air.
Under normal operating conditions, an engine may require only nominal coolant flow to maintain proper temperature of internal components. However, under severe conditions an engine requires increased coolant flow to maintain proper component temperature. If a high flow rate water pump is used to provide a high coolant flow rate under severe conditions to prevent engine overheating, the amount of coolant flow will be excessive under normal operating conditions, resulting in parasitic energy losses.
Since water pumps are commonly mechanically driven by an engine, the flow of coolant through the engine stops when the engine shuts down. The lack of coolant circulation after an engine stops allows engine heat to soak into the coolant which remains in the engine and slows the cooling process.
A method of more efficiently controlling engine coolant temperature and of continuing cooling of an engine after shut down is desired.